This section provides background information related to the present disclosure which is not necessarily prior art.
Lean burn engines provide improved fuel efficiency by operating with an excess of oxygen over the amount necessary for complete combustion of the fuel. Such engines are said to run “lean” or a “lean mixture”. However, this increase in fuel economy is offset by undesired pollution emissions, specifically in the form of oxides of nitrogen (NOx).
One method used to reduce NOx emissions from lean burn internal combustion engines is known as selective catalytic reduction (SCR). SCR, when used, for example, to reduce NOx emissions from a diesel engine, involves injecting an atomized reagent into the exhaust stream of the engine in relation to one or more selected engine operational parameters, such as exhaust gas temperature, engine rpm or engine load as measured by engine fuel flow, turbo boost pressure or exhaust NOx mass flow. The reagent/exhaust gas mixture is passed through a reactor containing a catalyst, such as for example, activated carbon or metals, such as platinum, vanadium or tungsten, which are capable of reducing the NOx concentration in the presence of the reagent.
An aqueous urea solution is known to be an effective reagent in SCR systems for diesel engines. Several current injector systems include mounting arrangements that position the injector a predetermined distance away from the exhaust pipe. Some injector mounting arrangements may be referred to as a “dog house” or “stand-off” style. Other current injector systems include mounting blocks that have cannulated projections that extend into the exhaust pipe. Such mounting blocks have injectors arranged thereon for communicating a solution through the mounting block and cannulated projection into the exhaust pipe. In many examples, such mounting arrangements may be difficult to quickly and accurately connect to an existing exhaust pipe, such as on a vehicle in the field.